cpython/Doc/c-api/memoryview.rst

64 lines
2.3 KiB
ReStructuredText

.. highlight:: c
.. _memoryview-objects:
.. index::
object: memoryview
MemoryView objects
------------------
A :class:`memoryview` object exposes the C level :ref:`buffer interface
<bufferobjects>` as a Python object which can then be passed around like
any other object.
.. c:function:: PyObject *PyMemoryView_FromObject(PyObject *obj)
Create a memoryview object from an object that provides the buffer interface.
If *obj* supports writable buffer exports, the memoryview object will be
read/write, otherwise it may be either read-only or read/write at the
discretion of the exporter.
.. c:function:: PyObject *PyMemoryView_FromMemory(char *mem, Py_ssize_t size, int flags)
Create a memoryview object using *mem* as the underlying buffer.
*flags* can be one of :c:macro:`PyBUF_READ` or :c:macro:`PyBUF_WRITE`.
.. versionadded:: 3.3
.. c:function:: PyObject *PyMemoryView_FromBuffer(Py_buffer *view)
Create a memoryview object wrapping the given buffer structure *view*.
For simple byte buffers, :c:func:`PyMemoryView_FromMemory` is the preferred
function.
.. c:function:: PyObject *PyMemoryView_GetContiguous(PyObject *obj, int buffertype, char order)
Create a memoryview object to a :term:`contiguous` chunk of memory (in either
'C' or 'F'ortran *order*) from an object that defines the buffer
interface. If memory is contiguous, the memoryview object points to the
original memory. Otherwise, a copy is made and the memoryview points to a
new bytes object.
.. c:function:: int PyMemoryView_Check(PyObject *obj)
Return true if the object *obj* is a memoryview object. It is not
currently allowed to create subclasses of :class:`memoryview`.
.. c:function:: Py_buffer *PyMemoryView_GET_BUFFER(PyObject *mview)
Return a pointer to the memoryview's private copy of the exporter's buffer.
*mview* **must** be a memoryview instance; this macro doesn't check its type,
you must do it yourself or you will risk crashes.
.. c:function:: Py_buffer *PyMemoryView_GET_BASE(PyObject *mview)
Return either a pointer to the exporting object that the memoryview is based
on or *NULL* if the memoryview has been created by one of the functions
:c:func:`PyMemoryView_FromMemory` or :c:func:`PyMemoryView_FromBuffer`.
*mview* **must** be a memoryview instance.